Aircraft stabilizer



June 2, 1925. 1,540,438

J. H. THOMPSON AIRCRAFT STABILI ZER Filed Oct. 26. 1922 l1 Sheets-Sheet 1 WHA/5355s A UUR/VERS June 2, 1925. 1,540,438

J. H. THOMPSON AIRCRAFT STABILIZER Filed OC'L. 26, 1922 ll Sheets-Sheet 2 NVENTO? /1 TTORNEYS June 2,"1925 1,540,438

J. H. THOMPSON AIRCRAFT STABILIZER Filed Oct. 26. 1922 l1 Sheets-Sheet 3 WITNESSES l/VVE/VT TTOHNEYS June 2, 1925. 1,540,438 f J. H. THOMPSON AIRCRAFT STAB ILI ZER Filed 061;y 26. 1922 ll Sheets-Sheet 4` WINES?? IN VEN TUR THoMPao/v A TTORNEVS June 2, 1925.

J. H. THOMPSON AIRCRAFT STABILIZER WSN@ Jue 2, 1925.

J. H. THOMPSON AIRCRAFT STABILIZER Filed Oct. 26, 1922 11 Sheets-Sheet 6.

www.

MN. .o mm.

@BW Q .QmNN hpfen TTOHNEYS WIT/M8858 June 2, 1925.

J. H. THOMPSON AIRCRAFT STABTLIZER Filed Oct. 26. 1922 /NVENTR J THOMPSON,

l1 Sheets-Sheet 7 A TTURNEYS June 2, 1-925. 1,540,438

J, H. THOMPSON AIRCRAFT STABILIZER Filed oct. 2e, 1922 11 sheets-s116131@ WIT/VESSES l/Vl/ENTR JH. THOMPON,

June 2, 1925..

J. H. THOMPSON AIRCRAFT STABILIZER Filed Oct. 26.

1922 11 Sheets-Sheet 9 M ...NL

June 2, 1925.

J. H. THOMPSON AIRCRAFT STABILIZER Filed Oct. 26. 1922 11 Sheets-Sheet 10 HV VEN TUR j( 7kg/2504,

4 TTORNEYS W/ TNESSES fdl/mf `lune 2, 1925. l

J. H. THOMPSNON AIRCRAFT STABILIZER Filed oct. 2e, m2 11 sheets-sheet 11 mp MM n H. f.

A TTORNE V8 Patented June 2, 1925.

UNITED STATES JAMES HENRY THOMPSON, OF HOLLIDAYS COVE, WEST VIRGINIA.

AIRCRAFT S'IABILIZIEl-Ri- Application led October 26, 1922. Serial No. 597,115.

To all whom t may concern."

Be it known that I, JAMES HENRY THOMP- soN, a citizen of the United States, and a resident of Hollidays Cove, in the county of Hancock and State of; West Virginia, have invented certain new and useful Improvements in Aircraft Stabilizers, of which the following is a specification.

My invention relates to improvements in stabilizing apparatus for aircraft andit consists in the constructions, combinations and mode of operation herein described and claimed.

An object of the inventiono is to provide apparatus which is primarily adaptable to aircraft of al1 types, its purposebeing to maintain thecraft on a substantially even keel during flight.

A further object of the invention is to provide apparatus to constitute an auxiliary to the manually controlled stabilizing devices of an aircraft, the purpose .of which apparatus is to automatically perform the functions of said stabilizing devices should the operator desire to have it so.

Another object of the invention is to provide stabilizing apparatus for aircraft which may be made to operate either manually or automatically. 1 l v A further object of the invention isto provide automatic stabilizing apparatuszfor aircraft comprising an arrangement of perpen dicles whichare intended to always maintain a-perpendicular position, certain rack bars being shiftable by virtue of this perpendicularity when the aircraft. departs from its horizontal flying plane to a predetermined undesired degree, thereby bringing certain fluid-operated devices, intoplayto actuate the provided stabilizing devices (ailerons, l rudders,.wing tips, etc)"to re-establish the craft in its aforesaid horizontal flying plane. Another object of the invention is to provide mechanically, electrically and fluid-op-y erated devices all of which cooperate in actuating the stabilizing means of an aircraftk in order to automatically keepthe aircraftv on an even keel A further object of the invention is to' provide a control which is auxiliary to both the automatic and manualcontrols, in the nature of an emergency control which` how ever, may be used interchangeably with the manual control.

Other objects and advantages will appear in the following speci tication, reference being had to the accompanying drawings, in which Fig. l is a diagrammatic perspective View illustrating the apparatus for actuating the ailerons of an airplane to thereby control the lateral stabilization thereof,

Fig. 2 is a diagrammatic perspective view which is intended .to be read in connection with Fig. l, illustrating the fluid-actuated apparatus for controlling the horizontal rudders and thereby the longitudinal rstabilization of the airplane, the accompanying Wiring diagram `being a duplication of the stabilizing mechanism in Fig, 1, in so far as the longitudinal rack bar and its switches are concerned,

Fig. Bis a diagram of the electrical partA cuits involved,

- Fig. is a section taken substantially on the line of Fig. 1, illustrating the pistons and `fluid-controlling.means therefor to actuate'the ailerons, also illustrating a part of the lateral perpendic'le with its rack bar and switchesso "as` to more readily associate this view with Fig. 3, in which connection it may be reet-j lFig. 6 isla` detail enlarged section of the left cylindervin Fig. 5,v

Fig.7 isa section on the line 7-7 of Fig.

p 6, illustrating the cam which gradually opens the air valve for slowly introducing airinto the left end ofthe' cylinder in Fig. 6, A Fig. 8 is a'section taken substantially on the line 8-,8 (if-Fig 1, the switch contact on the auxiliaryiclutch lever being shown c i the side nearest. the observer (reverse `from the showing l) so as to make the construction rnore comprehensive,

.Fig. 9 v"is sa Y, longitudinal section of the stabilizingapparatus, taken lsubstantially on the line 9-9 of Fig. l,

Fig. 10 is a cross section on the line 10-10' of Fig.` 9, showing the lateral stabilizing perpendicle and illustrating the action which -takes place when the plane tilts toward the right,

Fig. 11 1s a detail diagrammatic view showing how the rheostat in Fig. 3 will in practice be operated by a single knob,`

CII

Fig. 12 is a detail section on the line 12- 12 of Fig. 1, showing the construction of the post' and hand wheel by which the ailerons and horizontal rudders are manually controlled,

Fig. 13 is a detail section of one of the electrical switches, taken substantially on the line 13--13 of Fig. 1,

Fig. 14 is a diagrammatic perspective view showing the parts of said switch disassembled,

Fig. 15 is a diagrammatic perspective view of the aircraft hand lever and an associated arrangement of air and electro-inagnetic valves constituting an emergency control,

Fig. 16 is a section on the line 16-16 of Fig. 15, illustrating the construction of one of the electro-magnetic valves,

Fig. 17 is a diagram illustrating how the electro-magnetic valves cooperate with the air valves on the hand lever,

Fig. 18 is a diagrammatic perspective view of the rheostatic arrangement for regulating the closing of the lateral and longitudinal control air motors in Figs. 1 and 2, also illustrating the base frame by means vof which the entire apparatus isset -to conform to predetermined angles o-f ascent and descent, and

Fig. 19 is an elevation of the cover plate of one of the lamp panels (Fig. 1 for eX- ample).

The purpose of the invention is to provide a stabilizing apparatus for aircraft `comprising a pair of gyroscopic perpendicles, the first of which is arranged, through suitable electrical wiring, to control a fluidactuated mechanism which in turn operates the' ailerons, the second of which, through substantially identical electrical wiring, is arranged to control a second uid-actuated mechanism which in turn operates the horizontal rudders. The first gyroscopic per` pendicle is therefore, by virtue of its function, hereinafter termed the lateral control perpendicle, the second being termed the longitudinal control perpendicle by virtue of its function. The same plan of distinction is followed in respect to other mechanisms which are associated with these perpendicles.

It is intended that the aircraft on which the invention is installed shall move along a normally straightway course, lateral and longitudinal tilting within certain safe predetermined limits being allowed by the adjustment of the automatic stabilizing apparatus. As its name implies, this apparatus is intended to operateindependently of the will of the pilot or other operative in charge of the aircraft, and when the aircraft tilts either laterally' or longitudinally beyond a safe degree, the apparatus comes into play to operate either a`n arrangement of aileiaaaae rons, wing tips, ruddcrs, or the like, to restore the aircraft to its former flying position.

mght is not lost of the desirability of alternate modes of controlling the aircraft and provisions toward this end are made. in the automatic stabilizing apparatus mentioned above and in the usual manually operated apparatus by which the ailerons and rudders may be operated equally as well. The invention has the advantage of readily shifting over from one to the'other mode of control by simply pushing forwardly on two levers, such act immediately severing all electrical connections rendering the fluid-actuated control mechanisms entirely free. In addition to the automatic and manual controls, provision is made of an emergency control which comprises the use of the mechanism disclosed in Fig. 15. This comes under the category of manual controls and is intended to be used only in such cases when the motors or their connections fail. lVith this brief introduction, the reader will more readily understand the description of the general construction which, as already intimated, comprises the stabilizing apparatus 1, the lateral control fluid-actuated mechanism 2, the longitudinal control fluidactuating mechanism 3 and the manual control mechanism 4 (Figs. 1 and 2). rlhe stabilizing apparatus l and lateral control mechanism 2, constituting the greatest combined weight, will be suitably distributed around the center of gravity of the aircraft which, in the present instance, is located somewhere between the planes 5 and 6. rlhe invention is shown greatly out of proportion to the planes 5 and 6 in Fig. 1, the elements 1, 2 and 3 in actual practice being small enough for disposal in the fuselage of the aircraft without being 'in the way of either passengers or other mechanism.

Each end of the upper plane 5 is equipped at the ,trailing edge with an aileron 7 and S, these being pivoted at the points 9. Each aileron has a double arm l() and 11 to which cords 12, 13 and 14, 15 are attached (Fig. 1) these cords running over pairs of grooved rollers 1G and 17 so that they maybe properly led to their respective points of attachment to the double crank 18 of the lateral control mechanism 2.

The stabilizing apparatus 1 has two perpendicles, one of which (above called the lateral control perpendicle) comprising a gear 19, bridge 20, motor 21, centrifugal governor balls 22, a mercury globe 23 and a centrifugal ring 24. Parts of the second perpendicle corresponding with those just described in the first perpendicle are respectively designated 25, 26, 27, 28, 29 and 30. The motors 21 and 27 are intended to operate continuously while the aircraft is in flight, the resulting centrifugal action of the lill).

lll)

governors 22. 28 and rings 24, 30 maintaining the perpendicles in perpendicular positions so` that should the aircraft tilt either laterally or longitudinally beyond a safe degree, the rack bars 3l and 32 will be shifted to change some of the electrical circuits either in Fig. 3 or 'in Fig. 2, depending on whether 'it was the lateral control rack bar 3l or the longitudinal control rack bar 32 that was shifted.

Assume that the aircraft tilts toward the light in the direction of the arrow a (Fig. .1). The perpendicle 21 in seeking to re-establish itself in the perpendicular position, will shift the rack bar 3l toward the left in the direction ot' the arrow I) (Figs. 1 and 4) causing the left switch 33 (of which the right switch 34 is a counterpart) toA reverse the direction of an electrical current through the left valve motor 35 (compare Figs. 3 and 4) of which the right valve motor 3G is a counterpart, thereby causing fluid under pressure to flow into the cylinder 3T (Fig. 5) of the lateral control mechanism 2. This fluid drives the piston 38 toward the right, moves the piston rod 39 in the same direction, 'shifts the arm 4() in a counter clockwise direction, the double crank 18 in the same direction (arrow r',- Fig. 1) thereby pulling the cords 13 and y14, slackening the cords 12 and 15 so that the aileron T is lowered, the aileron 8 raised (dotted lines. Fig. 1) causing the right end of the aircraft to be elevated and thus restored to the former flying position.

An operation similar to the one described above takes place when the aircraft tilts either up or down beyond a predetermined safe degree. Assume that it tilts down in the direction of the arrow (Z (Fig. 2 The perpendicle 2T. seeking to maintain the perpendicular position` will shift the rack bar 32 rearwardly in Fig. 1 and to the left (arrow e) in Fig. 2, shifting the switch 41 (of which the switch 42 'is a counterpart). reversingl the flow of current through the valve motor 43 (of which the valve motor -1-lis a counterpart) thereby admitting fluid under pressure to the cylinder 45. whereupon the arms 46 are rocked cmlnter-clockwise (arrow f) the double crank 47 rocked in a similar direction (arrow g) causing a pull onthe cords 48, 49 anda. slackening on the cords 5()7 51. i

These. cords are crossed as shown, and respectively connected to thel upper and llower ends of double` arms 52, 53 of theelevators 54. The pull on the cords 48 and 49 causes the elevators 54'to rock o-n theirhinged n'1ounting55 until they assume the dotted line position. This position causes the aircraft to swerve upwardly so that it again seeks its normal flying position. The reverse operations of both the lateral and longitudinal control mechanisms involve,

similar parts which are associated with tho e. described in the foregoing operations. Th se parts are described in detail below7 beginning with the description of the stabilizing apparatus, which has a frame composed of channels 56 and end pieces 5T.. 'lhe end pieces have trunnions 58 which are made hollow for the purpose of the passage of wires as in Fig. 18. The trunnions are located below the center of the frame so that the shifting movement of the perpendicle 21 when it seeks the perpendicular position upon the lateral tilt-ing of the airgraft, may more readily take effect on the rack bar 31. The trunnions are mounted in bearings on the end pieces of a base frame 59 which thus supports the. entire automatic stabilizing apparatus.

The base frame 59 serves to set the entire stabilizing apparatus to conform to predetermined anglesof ascent and descent of the aircraft. In other words, when the aircraft assumes a predetermined ascending angle, it is necessary to bring the stabilizing apparatus to a level so that it may properly function, and similarly, when it assumes .the descending angle the apparatus must again be brought to a level for the same purpose. This changing of the position of the base frame 59 occurs only in ascending and descending, and for the purpose of making the changes provision is made of a lever 348 which has a connection 349 to a crank 350 on a suitably supported shaft 351 to which the side members of the frame 59'liave fixed connection.

Recesses 352, 353 and 354 in a quadrant 355 designate the places to which the lover 348 must be moved in order to assume the ascending, descending and normal positions. Upon moving the lever 348 forwardly to engage the recess 352, the base frame 59 will be rocked toward'the right. to compensato for the ascending angle of the.` aircraft. )Vlien the lever 348 is moved to engage the. recess 353, the reverse. will be the case.

Referring again to the frame 56s experimentation has shown ythat the frame will rock far more readily when the trunnions 58 are placed below the center than when they are `placed above, theformer arrangement therefore being "taken advantage of because quick action is desired'in'the` 'stabilizing apparatus. The gearsl9'and 25,l mentioned in f the preceding description,` are semi-globular in shape :because they must maintainftheir engagement lwith the teeth 60 and 6l ofthe respective rack bar`s'31 and 32 during both theV lateral and longitudinal movements ofthe aircraft. c

' The teethof .the semi-globular gears 19 and 25 arey disposed 'at right angles to each other (Figs. land 9) so that one may slide in respect to its rack bar while the other grips the teeth of the other rack bar to shift it for the purposes mentioned above. For example, when the aircraft tilts toward the right (arrow a., Fig. 1) both perpendicles 21 and 27 will move together, as they always do, in seeking to re-establish their perpendicular position, the semi-globular gear 19 at such time shifting the lateral rack bar 31 by virtue of the gripping engagement with the teeth 60, the semlo ular gear 25, however, partaking of a sliding -gtion in respect to the teeth 61 because of'tlie right angular disposition of its teeth in respect to the gear 19. Should the aircraft tilt to the front or back, a reverse operation will result.

Ability for adjust-ment of the perpendicles 21 and 27 when the aircraft tilts longitudinally, is provided for by pivotally mounting the bridges and 26 on the side channels 56 as at 62 (Figs..r1 and 5). -rLike the pivots of the frame 56,'tlie pivots- 62 of the bridges are located below centers so that the bridges and the associated parts may more readily be susceptible to longitudinal tilting movements of the aircraft. lhe bridges are joined by connecting rods 63 which have pivotal mountings 64 (Fig. 9) on each of thebridges. Each motor 2 1 and 27 is supported from the adjoining bridge by brackets 65 (Figs. 1 and 5) `so that the motors are held in a rigid state.

The shaft 66 (using the motor` 21 as an example) extends through at the bottom (Fig. 9) sufficiently far to enable screwing or otherwise fastening the mercury globe 23 in place. A sleeve 67 is disposed between the motor and the mercury globe, the sleeve having a plurality of ears 68 to which the arms 69 of the governor balls are pivoted. An equal plurality of dash pots 70 have spring-actuated plungers 71 which bear upon the arms 69 and are intended to enable lightening the weightvof lthe governor balls and yet make it necessary to attain a high rotational speed before the governors assume the horizontal positions. The function of the governors 22 and 28 is to aid in keeping the perpendicles in the perpendicular position, and upon the slightest manifestation of the latter to leave such position, to immediately restore the balance of the perpendicles and cause them to resume the proper position.

This is accomplished the dash-pot. plungers. before) bear upon the governor arms so as to prevent them from raising higher than the horizontal. Now, .should either perpendicle depart from the perpendicular it would in effect move closer. to one side of the governor and thus upset the balance. The governor, being compelled by said dashpot plungers to remain in the horizontal position, now drags the perpendic-le back to the original perpendicular position and by the action` of tion.

These (as statedv so restores the balance of the perpendicle which is necessary to the desired operation of the apparatus. It is to be noted in Fig. 9 that before the governors are set in motion, they rest in a position against the mercury globe as illustrated in dotted lines in the case of the governor 28 of the perpendicle27. -The lungers of the dash pots are then in s uci proximity'as to immediately engage the governor arms and resist the tendency of the governor to reach the horizontal position upon the initial operation. lt is not until a high speed is attained that the governor has overcome the dash ots suiliciently to enable it to assume the iorizontal and operating position.

A quantity ofniercury 72 is confined in the globe 23, this mercury moving up the wall of the globe under the influence of centrifugal action until it assumes substantially the position shown in dotted lines. Any tendency of the perpendicle to depart from the perpendicular position in which itis intended to stay, will tend to upset the balance established by the whirling mercury, whereupon the body of mercury will tend to gravitate toward the unbalanced sideand so assist in pulling the perpendicle back to the aforesaid perpendicular posi- The governor balls 22 and ring 24 serve Vto keep the perpendicle in the perpendicular position by centrifugal force, whereas the function of the mercury globe 23 is more intended to fulfill this function by the direction action of a gravitating substance. `T hegloloe 23 and ring 24v are connected by a universal joint .73 which aids the ring n keeping its horizontal whirling position should there be any tendency of the rest of the perpendicle toward departing from the perpendicular position.

Lateral tiltin movements of the aircraft result in the s ifting of the rack bar y31 through the medium of the perpendicle 21, asstated before, and to repeat Lne example given, a tilting movement toward the right will cause a movement of the rack bar 31 toward the left. `This rack bar has a plurality of teeth 74 (Fig. 3) which are adapted to engage the single teeth 75 and 76 of` the switches 33 and 34, depending on the lll) direction in which the rack bar is shifted.

In Fig. 4, the aircraft is shown as having tilted to such a degree as would bring the first ofthe teeth 74 (at the left) into engagement with the single tooth 75 of the switch 33. Should the plane tilt over still farther, the first tooth will move past and bring the second into engagement with the single tooth '7 5 and thus serve to keep the switch 33 shifted.

The purpose of this switch, as well as. that of the switches 34, 41 and -42 (Fig. 2) is to reverse the direction of the flow of electrical currents through the valve con- Cil trollingmotors 35, 36, 43 and 44. Under normal flying conditions, current flows from the positive bus 77 (Fig. 3) over wire 78 to the rear Contact 79 of switch 33, thence overv Wire 80 to the lamp 81, wire 82, through the movable arm 83 and resistances 84 of the rheostat 85, wire 86 to the arm 356 of the automatic rheostat 357 (Fig. 18), long contact 358, Wire 359 to motor 35. returning via wire 87 rear contact 88 ot' the switch 33 and back to the negative bus 89 via wire 90. r[his passage ot cur rent keeps the motor energized so that it tends to turn in the clockwise direction (looking down) as indicated by the dotted arrow in Fig. 7.

But this tendency of the motor 35 to rotate is checked by the engagement of a pin 91 on the motor shaft 92 with one side of a stop pin 93 which is fitted in the adjacent motor bearing 94. The motor 35 (as well as the other three valve motors) is enabled to make almost an entire revolution, advantage being taken of this feature to priovide a cam 360 by means of which air is gradually admitted to the cylinder 37, the amount of air admitted depending upon the degree of rotation of the motorshatt.

A shifting of the switch 33 will reverse the direction ot the flow of current through the motor 35 (Fig. 4) current then flowing from the positive bus 77 over wire 78 to the front contact 95 ot the switch 33, over wire 96 to the lamp 97, wire 98 to the movable arm 99 of the rlieostat 100, over the contacts and resistances 101 of the rheostat to the wire 102 tothe motor 35, returning via wire 86, branch 103 to the other front Contact 104 of the switch 33 and back to the negative bus 89 via wire 90.

This reversal ot the current causes the motor shaft 92 to revolve in the direction opposite to the arrow in 7, so that, should the aircraft have tilted a great degree, the pin 91 will engage the other side ott the stop pin 93 where it is checked. The almost complete revolution of `the motor shaft thus represented, will serve to have gradually admitted air to the cylinder 37 so that the piston 38 will have been moved over about to thek limit. It the aircraft tilts only to a slight degree, the reversal of current through the motor 35 will last but an instant before the original current direction is restored, whereupon the motor will promptly etfect the shutting ofi' of air to the cylinder 37. It will thus be seen that there will be periods in the operation of the stabilizing apparatus when the motor shaft 92V will turn more or less than at other periods, this being controlled by greater or less degrees of lateral tilting of the aircraft. v

The varying points of cut-ofi' of the valve motor 35 (and 36) determine various degrees of movement of the piston 38, and as the movements of the piston 38 determine the amount of tilting of the ailerons 7 and 8 (Fig. 1) it is imperative that the a'ir be promptly cut olf at the proper time so that excessive adjustments of the ailerons will not result. It is anticipated that the move ments of the motors 35 and 36 (also 43 and 44 in the longitudinal stabilizing apparatus) are not fast enough to accomplish the desired quick response. Electro-magnetic cut-oli' valves 342 and 347 are therefore interposed in the supply air lines which lead to the respective pairs of valve motors. This valve (taking valve 342 in Fig. 3 as an example) is normally seated by a spring 343 to keep the air line to the valve motors closed. .nergization of the electro-magnet 344 will unseat the valve to open the air lines and this energization occurs when the aircraft tilts either to the right orto the left, at which times current will flow through either shunt circuit 345 or 346 accordingly as switch 33 or 34 becomes operative.

Due to its ability to act quicker, the electro-magnetic valve 342 will open fully as the valve motor 35 begins to rotate, and again, due to its ability to act quickly, the valve 342 will close to shut off the air supply immediately upon reversal of the switch 33 (for example) when the aircraft starts to right itself. This may occur at a time considerably before the motor 35' begins to reverse, and it must be obvious to the reader that the shutting oli of the air supply should not have to Wait until the motor `35 is completely reversed but should occur vpromptly upon the beginning of the righting of the aircraft.

Mention has been made of the motor sha-.tt 92 carrying a cam 360. This cam is intended to operate an air valve 105 to con` trol the passage of air through an arrangement of longitudinal grooves 106. Communication between the left end of cylinder 37 and the atmosphere is had through an exhaust valve 107 which is normally kept open by an eccentric 361 on the shaft of the motor. Under normal conditions the valve 105 is kept closed by a spring 362.l

The eccentric 361 moves from beneath the stem of the valve 107 when the motor '35 is reversed, thus closing the exhaust passage a little before the valve 105 is opened to the pipe 108 of the compressed air tank 109. l

Under the same normal flying conditions, current is furnished to the other lateral control valve motor 36, ycurrent flowing from the positive bus 77 (Fig. 3) over wire 110 to the rear contact 111 of the switch 34, thence over wire 112 to the lamp 113, wire 114 to the movable arm 115 of the rheostat 116, over the resistances and contacts 117 to the wire 363 to the arm 364 of the automatic rheostat 365, over the long contact 366 to wire 118 and the motor 36, returning via wire 119, rear contacts 120 of the switch 34, then over Wire 121 to the negative bus 89.

Since the motor 36 is energized, the shaft 122 tends to turn but as in Fig. 7, is checked by the engagement of a pin 123 on the shaft with a stop pin 124 on one of the bearings 125 of the motor. The shaft 122 carriesa cam 126 (Fig. 5) which is adapted to operate an intake valve 127 and also carries an eccentric 128 normally keeping the eX- haust valve 367 open until a reversal of the motor 36, occurs as described in connection with the motor 35 in Fig. 6. The open exhaust valve 367 keeps the right end of the cylinder 129 (which is the counterpart of cylinder 37) in communication withethe atmosphere.

A shifting of the switch 33 will reverse the direction of the flow of current through the motor 35 (Fig. current then flowing from the positive bus 77 over wire 78 to the front contact 95 of the switch 33, over wire 96 to the lamp-1 97, wire 98 to the movable arm 99 of the rheostatI 100, over the contacts and resistances 101 of the rheostat to the Wire 102 tothe motor 35 returning via wire 86, branch 103 to the other front contact- 104 of the switch 33 and back to the negative bus 89 via wire 90. A reversal of the energizing current of the motor 36 occurs when the aircraft shifts toward the left instead of toward the right, as in the example just given. No illustration of this occurrence is made in the drawing, but the currentflow at such time is over the following circuit:

From the positive bus 77 (Fig. 3) over wire 110 to the front contact 130 of the switch 34, wire 131 to the lamp 132, wire 133 to the movable arm 134 of the rheostat 135, over the contacts and resistance 136, Wire 119 to the motor 36 whence the current `returns via wire 118, branch 137. front contact 138 of the switch 34 and back to the negative bus 89k via Wire 121. This rei'ersal of the current ,in the motor 36 is accomplished by the shifting of the rack bar 31 toward the right and the consequent shifting of the switch 34 through the engagement of the first of the teeth 74 with the single tooth 76. The reader will have observed from the foregoing description that the automatic rheostats 357 and 365 (Figs. 3 and 18) are situated only'in the normal energizing circuits of the motor 35 and 36.

Assume now that the aircraft has tilted to a marked degree toward the right (arrow a Fig. 1). -The arms 356 and 364 of the automatic rheostats 357 and 365 being fixed on the hollow trunnions58 of the frame 56, will both move toward the left, the arm 356 traversing a number of the contacts and resistanees 368, the arm 364 moving farther oyer the long contact 366. The purpose of the resistances 368 (and 369 inthe case of thel rheosta-t 365) is to insure suiiicient retardation in the reversal of the motor and the accompanying closing of the valve 105 (Fig. 6) as to hold the'ailerons 7 and 8 (Fig. 1) in their adjusted positions until the aircraft approximately reaches the righted position.

The reversal of the motor 35 and the closing of valve 105 is accelerated as the arm 356 traverses the contacts 368 toward the right, the left endof the long contact 358 extending far enough beyond the vertical center of the automatic rheostat 357 to insure the complete reversal of the motor and a consequent opening of the exhaust valve 107 at about the time that the aircraft reaches the corrected position, and thus prevent'l the possible chance of overright-ing the aircraft. The same mode of operation is carried out in respect to the rheostat 365 when the aircraft tilts toward.

the left.

An indication of the flying position of the aircraft is given by the electric lamps on the panel 139 (Fig. 1), these lamps giving reference to the position of the aircraft. so far as thelateral stabilization is concerned. Asecond panel 140 (Fig. 2) has another arrangement of lamps which indicates the flying position of the aircraft so far as longitudinal stabilization is concerned. yUnder normal iiying conditions, the lamps 81 and 113 (Fig. 3) are lighted, the circuit over which current is furnished thereto having been described above. Situated in the middle of eac-h panel 139 and 140 is a blue lamp 141 and 142. This lamp is intended to be lighted permanently by current from the main positive feeder 143, Wire 144, branch 145,.the current returning to the main negative feederv 146 via branch 147, Wire 148. Similarly, the feeder 143 (Fig, 2) furnishes current to vthe lamp 142 via lwire 149, returning to the negative feeder via wire 150. v

The lighting arrangement described is adapted primarily for night flying. and bv .observing the panels 139vand 140 the pilot can ascertain Whether the aircraft is flying level or not. Under normal-conditions,

the lamps 81 and 113 are lighted,the purpose of these lamps being to define a base line whichv indicates that the plane is level latera1ly.- "Should the aircraft tilt-toward the right, the lamp 81 will become extinguished, due to the breaking ofthe circuit at the rear Contact 79 (Fig. 3) and the lamp 97 will be lighted, due tothe establishmentv of a new circuit atvthe frontcontact 95 (Fig. 4). v

In order to suitably dim the lamps and Cai obviate the glare inthe eyes of the opcrator, a pane of glass 338 (Fig. 19) is suitably mounted over the lamps 81, 97, 13:2 and 113 and 141 of the panel 139. This pane is painted a dark color, leaving crossed arrows 339 and 349 clear. rFliese arrows, and the corresponding lamps,A are partitioned as at 341 so that either arrow will be illuminated upon lighting,T of the respective sets of lamps and thus clearly indicate to the operator the direction of inclination of the aircraft.

Accordingly, an inclination toward the right will be disclosed by the appearance ofv a diagonal arrow across the panel 139,7'

formed by the lamps 97, 1'41 and 113, this arrow slanting' in the direction toward which the aircraft is tilting. The blue lamp 141 serves the purpose of a pilot light in reference to which the other lamps on the panel become lighted to show the pilot,

that the aircraft is either on an even heel or is tilting to one side or the other. Should the aircraft tilt toward the left, the lamps 81 and 132 (Fig. 3) would appear lighted on the panel 139, illuminate the other arrow 339, and thus indicate to the pilot that the 'aircraft is tilting toward the left.

1n order that the aircraft may be controlled automatically so far as longitudinal stabilization is concerned, Ian arrangement substantially identical with that disclosed iii-Fig. 3, is used. Under normal dying conditions, both valve motors 43 and 44 are energized, thus tending to turn in such a direction as will keep the associated air valves closed. rlhe drawings do not show these air valves in detail, the showing in Fig. 5 (which belongs to the lateral control mechanism) being",r relied upon to acquaint the reader with the longitudinal control mechanisinin Fig. 2 since both are identical in construction. Current for the normal energization of the motors 43 and 44 flows over the following,r circuits:

From the main positive `bus 77 (Fig. i?) over wire 151 to the rear contact 152 of the switch 41, over wiie 153 to the lamp 154 on the panel 140, over wire 155 to the movable arm 156 of the rlicostat 157, over the contacts and rcsistances 158, and wire 369 to the arm 370 of the automatic rlieostat 371 (see also Fig. 13) over the long contact 372, wire 159 to thc motor 43 whence. it returns via wire 169, wire 161, rear contact 162 of the switch 41, thence back to the negative bus 39 via wire 163.

Similarly, the motor 44 is energized by current flowing from the bus 77 over wire 164rearfcontact 165 of the switch 42, wire v 166, lamp 167 of the panel 140, wire 168 to the movable arm 169 of the rheostat 179, over the contacts and resistances 171 and wire 373 to the arm 374 of the automatic rheostat 375 (see also Fig. 18), long contact blue pilot lamp 142, remain lighted while the aircraft remains in the desired flying` level, but should the aircraft tilt longitudinally, the pilot will be apprised of the danger by a change in the signal light, thelamps of the panel 14() having' a coveringpane :ir-

rang'ed on the same order as the pane 338 over the panel 139 in Figs. 1 and 19.

For example, should the aircraft tilt. downwardly toward the front, as indicated bv the arrow (Z in Fig. 2. the rack bar 32 'will be shifted in the directii'in of the arrow e as described before. bringing` the tirst of a plurality of teeth 177 on top of the rack bar into engagement with the single tooth 178 of the switch 41, thereby shifting the switch in a manner precisely like. that in which the switch 33 in Fig. 4 was shifted. Current will then flow over wire 151 2) front contact 179 of the switch 41, wire 189 to the lamp 181 on the panel 140, wire 182 to the movable arm 183 of the rheostat 1854-, over the contacts and resistances 185 and wire 186 to the motor 43, whence it returns via wire 159, branch 187 to the front contact 188 of the switch 41 and returning to the negative bus 89 via wire 163.

Under this circumstance, the lamps 181, 142 and `167 would be lighted on the panel 140 and indicate to the pilot that the aircraft was tilting' downwardly at a dangerous anglo. The lamp 154 becomes extinguished at the. breaking,r of the circuit at the rear contact 152 of the switch 41.

The foregoing' reversal of the current through tbe motor 43 will cause the opening of the associated valve 189 so that pressure fluid flows into the cylinder 45 (Fig. 2) and drives the piston 19t) toward the right so that the arms 46 are shifted in the counterclockwise direction (arrow f) and the elcvators 54 are moved into the dotted line positions as already described above. But bcfore air can enter the valve 189 it is necessary that the electro-magnetic opening,` valvc 347 (described before 'in connection with the valve 342 of Fig. 3) be opened, such opening,r ha ving occurred upon the cnergization of thc shunt circuit 377 from the circuit which was completed across the front contacts 179 and 188. The completion of a similar circuit by the switch 42 closes another shunt circuit 378, again for the purpose of opening the electro-magnetic valve 347 andin turn to open the air line to the valve of inotor 44.

Should the aircraft tilt in the opposite direction, that is to say, down at the rear, the reverse actions would take place, current then flowingr from the main positive bus lill) 77 over wire 164 to the -front contact 191 of the switch 42 (the rack bar 32 being presumed to have been. moved toward the right and the switch 42 to have been shifted) over wire 192 to the lamp 193 on the panel 140, over wire 195 to the movable arm196 of the rheostat 197, over the contacts and resistances 198 and wire 173 to the motor 44, whence it returns via wire 172,l branch 199, front contact 200 of the switch 42 and then back to the negative bus 89 via wire 17 1t is readily seen that under this circuxnstance the arrow indicated across the anel 140 by the lamps 193, 142 and 154 will be inclined oppositely to the one formerly described and will indicate to the pilot that the plane'is tilting toward the rear. The lamp 154 remains lighted because the original circuit through the motor -43 remains undisturbed at the rear contact 152 of the switch 41 when the rack bar 32 is shifted toward the right. For the same reason, the lamp 167 remains lighted when the rack bar 32 is shifted toward the left (arrow e). The lamps 181 and 193 are lighted only when the circuits of the respective motors 43 and 44 are reversed.

Provision is made for the utilization of the signal panels 139 and 140 eveny after the apparatus has been shifted into manual control, at which time all of the electrical devices, aswell asthe fluid-actuated mechanisms, are disconnected and therefore incapable of operation. Both blue lamps 141 and 142 remain lighted under this circumstance, since these lamps draw current from such places in the main feeders 143. and 146 as would not be affected by the shifting of either auxiliary clutch lever 201 or 202. These auxiliary levers control the entrance of electrical current from'the main feeders.

143 and-146 to the busses 77 and .39 over the lateral and longitudinal stabilizing apparatuses respectively.

For this purpose, the auxiliary lever 201 has a contactor 203 which in the normal flying condition unde automatic control cngages the contact 04 (Fig. 3) and estublishes a flow of current from the main positive feeder 143, wire 205, contacts 203 und 204` and wire 206 to the positive bus 77, the current returning from the negative bus S9 via the main negative feeder 146 when any of the various electrical devices, Vconnected in parallel across the busses, is closed. 1n shifting the auxiliary lever 201 for manual control, the contactor 203 will engage the contact 207. thereby partially closing a circuit from the main positive feeder 143, wire 205 and contacts 203, 20T tothe wire 208. This wire embraces lamps 209 and 210 from which wires 211 and 212 run to roller contacts 213 and 214. Companion roller cont-acts 215 and 216 have connections 217 and 218 to the negative bus 89.

Contact strips 219 and 220 are insulatively mounted on the respectiveends of the rack bar 31,the purpose of these strips being to bridge the gap between the contacts 213, 215 or 214, 216 and complete the circuit which was partly completed at the contact 207 by throwing over the auxiliary clutch lever 201.

.Assume the clutch lever to have been thrown into this position and the aircraft to be under` manual control none of the electrical devices (excepting the motors 21 and 27, and the lamps 141 and 142 which must be maintained at all times) are now in operation. Assume that the aircraft has tilted toward the right (arrow a, Fig. 1) this resulting in shifting the rack bar 31 toward the left. Upon bridging of the contacts 213, 215 by the strip 219, current will flow from the main positive feeder 143 over wire 205, contacts 203 and 207 to wire 208, through lamp 209, over wire 211 and over contact members 213, 219 and 215 to the wire 217 thence back to the negative bus 89 and negative feeder 146. The pilot will see the illuminated lamps 141 and 209 only but this illumination represents enough of a diagonal line to indicate to him that the aircraft is tilting downwardly toward the right. A similar indication (reversed) would be obtained by a lateral tilting of the aircraft toward the left, at which time the lamps 141 and 210 would be illuminated.

According to a similar plan, electrical signals indicating the position of the aircraft in reference to its longitudinal stabilization, are given,.while under manual control. The panel 140 (Fig. 2) has lamps 221 and 222 which are respectively lighted when the strips 223 or 224 bridge the adjoining contacts 225` 226 or 227, 228, Then the aircraft is flying under automatic control, the contacter 229 on the auxiliary clutch lever 202 (Fig. 2) is in engagement with a Contact 230, thereby completing a circuit to the busses 77 and 89 from the main positivo feeder 143 via wires 231 and 232. But when the aircraft is under manual control the lever 202 assumes a position .that is shifted from thc position illustrated in Fig. 2 so that the contacter 229 engages a contact 233 which partially closes a circuit einhraciug the linups 221 and 222.

Connection is iliade between these lamps and the contact 213 by a Wire 234, the respective lamps boing connected to thel contacts 226 and 22H hy wires 235 and 2.36, respectively. 'llwy contacts 225 and 227 are connected to the negative bus 89 by wires 237 and 28H, Assnnictluit the aircraft tilts longitudinally inthi` limiet-ion of the arrow (i in Fig'. 2 while nadar manual control. The rack liar '32 'will nuwe toward the left (arrow c) bridging the contacts 225 and 226 by the strip 223 an that current will flow 'from the main feeder 143 over wire 231 toi the contactor 225). Contact 233, wire 234. lamp 221, wire 235, contact members 226, 223 and 225 to the wire 237, negative bus 8S) and back to the negative feeder 146.l

The lamps'221 and 142 will now be illuminated before the pilot and will represent enough ot a diagonal line to indicate that the aircraft is tilting forwardly in the longitudinal direction. A similar result is obtained when the aircraft tilts rearwardly in the longitudinal direction, at which time the lamp 222 will become illuminated by virtue ot' the bridging of the contacts 227 and 228 by the strip 224 by the movement of the rack bar 32 to the right.

A red signal lamp 239on the panel 140 is intended to be lighted only when the aircraft tilts in the direction of the arrow Z (Fig. 2) to an extremely dangerous degree. This lamp is controlled by a pair of contacts 240 which are intended to be bridged by the strip 223 when the aircraft assumes a position such as described. At such time, current will flow from the main positive feeder 143 over wire 231, contact 233, Wire 234, lam 39, Wire 241, past the contacts 24() (which are presumed to be bridged by the strip 223), and Wire 242 to the negative bus 89. Since the lamp 221 is in circuit with the lamp 239 it too will be lighted, but thisis of no disadvantage since the indication given will be that of the forward and downward tilting of the aircraft, the two lamps 221 and 239 being read together with the blue lamp 142 and as one of the components ot' the imaginary line between the lamps.

The construction of one of the valve motor reversing switches is shown in detail in Figs. 13 and 14, the switch 33 being selected for description as all of the other switches 34, 41 and 42 are identical in construction and mode of operation. A pair of disks 243 and 244 is fixed on a shaft 245 by means ot' keys 246 or otherwise, the shaft in turn being fixed on a suitable bracket 247 which must be made so as to reach van adjacent place of support. No attempt at an accurate illustration of either the con struction of the bracket or the place of support has been made, other than to give a general idea as to what' the arra'ngen'icnt should be like (Fig. 10).

A disk 248 revolves on the shaft 24.5 in the space between the tixed disks 243 and 244, the revoluble disk carrying oppositely directed pairs ot' brushes 249, 250 and 251, VThese brushes cooperate with the airs ot' rear contacts 79, 88 and pairs of trontcontacts 95, 104, as were Adescribed in con-I nectionv with F igs. 3 and4. The brushes are. pressed outwardly by springs 253, and sul.)- staniially the whole structure ot each-pair `of brushes is enclosed by a copperl casing 254 to which the Wires 78 and 96 are respectively connected.

A pair 'of 'coil springs 255 and 256 arel provided for the purpose ofkeepmg the revoluble switch disk 248 in the normal-'position indicated in Fig. 3 when the single tooth is free ofthe teeth 74fon the rack bar 31. One endet each of these springs 4 is Afastened into an adjacent 'disk 243, 244, the other end of each spring being formed into a hook 257 for engagement byhookshaped pins 258 and 259 on opposite sides of the revoluble disk. The hooks 257 are the tooth 75 is freed, the tendencies ofthe v springs 255 'and 256'are to balance the revoluble disk and hold it in such position,

that electrical contact is made with the rear contacts 79 and 88 as described before.

Adjustments of the rheostats 85, 100,' 116 and 135 (Figs. 3 and 4) are made by a single knob .260 on the electric rlight panel 139. Figs. 3 and 4 show two adjustinr knobs but this showing is made vmerely tigor the purpose of aiding the construction of the diagrams and is not intended to be carried out in actual practice, thev correct arrangement being shown in Fig. 11. Here the knob 260 is shown connected with a gear 261 with which the plantary gears 262, 263, 264 and 265 mesh. These gears carry the arms 83, 99, 115 andr 134 of the various rheostats described in connection with Figs. 3 and 4, it being obvious from the construction shown that a turn in either direction of the knob 260 Will adjust the various rheostats so as to either increase or diminish the amount of current Which it is intended shall pass through.

The lateral control mechanism which has already been partly described in connection with the stabilizing apparatus in Fig. 1, comprises a pair of opposed pressure cylinders 37 and 129 (previously described) at the outer ends of which are located pairs of automatic vquick-release valves 266 and 267. The respective pairs of valves `have common pipe connections 268 and 269 with the cam chambers 270 and 271 ofthe valves 105 and 127. Interposed in the pipe connections 268k and 269 are electro-magnetic closing valves 379 and 380 which are normally ,open and do not come kintoV play to close the pipeconnections until the emer f gency control (Fig. 15) is brought intooperation. The purpose in providing duplicate valves 266 .and 267l 1s to effectV a quick and complete release of the pressure fluid when one or the other of the valves 

